Mavlink 3DR 433Mhz + RFD900 + Bluetooth + Serial + ANT+

There has been some projects around turning Mavlink via 433/900Mhz radios into Bluetooth to allow easy multiple use from laptops and tablets. There is also experimental code to allow the 3DR radios to use multiple receivers to allow a radio on tablet & ground station.

My idea is as follows:

  • Two radio inputs - Auto switch between, e.g. 3DR 433 & RFD900 - allow me to switch models and make no changes to my setup, automatically selecting which has link.
  • Serial / USB connection - I don't want bluetooth or the overheads with bluetooth for my ground station, direct connection pass through to the current radio is important.
  • Bluetooth - love the idea of local bluetooth for tablets
  • Simple display - built in display using a simple OLED output, just nice to look at the source both for the configuration of the device, which radio is used etc, but also basic mavlink information.
  • ANT+

The last entry there is probably the most unusual part. ANT+ is a protocol which is used by sensors such as heart rate and speed/cadence on bikes. It is common on watches for example. I would love to have ANT+ output to allow me to use some interesting devices coming up. For example you can buy heads up displays for sunglasses with ANT+ - yes we can do our own heads up display, nicer, but I like the off the shelf options.

What else would you do/add? Would you try and transmit to one of the other telemetry protocols.

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I don't understand what you're trying to do...  Just not sure what problem you're trying to solve.

Why would you need to switch between radios?  If you get a valid packet from ANY source it should be acted upon.  Are you trying to turn off radios to save power?  There wouldn't be any point to doing this on the ground side, and if you turn off air radios then you risk losing communications.

I'd also beware jamming any stupid standard into the thing for no good reason.  Sounds like you'll already have 3 radios going, so it's probably a bad idea to just keep stacking on shabby radios in such close proximity.  Add in cellphone and wifi and you'll ALREADY have FIVE radios going.

Hi Jake

  • Switch between radios - As far as I can see APM Planner only connects to one Telemetry radio at a time. If you say it can connect to multiple then one problem half goes away. Not really though, because trying to get which radio going to the other systems won't work that way. ie. Only APM planner would then be solved. But I can't see anywhere in APM Planner to connect to two radios. My ideal is just turn on. If I want to use my short range 433Mhz radio, or my long range 900Mhz radios, I don't want to change a thing
  • Saving power - no, don't care about 1Amp from the long distnace radios being used on the ground.

The radio selection though is the 1% of this job. It is convenient. Sure I could unplug one radio and plug another one in depending on which UAV I am flying, but nice not to have to :-)

The main part of this is retransmitting the data to other devices. Bluetooth - now I can use larger ground station and my tablet on my transmitter concurrently.

And I can wear my ANT based sun glasses with heads up display data such as height, speed etc which requires the data to be tranlated from Mavlink into ANT.

But multiple radios is a red herring above - they are not running together, just convenience for switching. Maybe most people only have one vehicle and one radio set, so not interesting. But I have 4 UAVs and two different radio sets that gets switched in and out and it is only growing.

> And I can wear my ANT based sun glasses with heads up display

Why not just use existing standards?  I'm just not sure where the problem is here.  Do the glasses come with no way to use them?  Everybody has to invent their own TX to use them?

Seems like you just want MP to connect to these existing devices.  That seems like a far easier project than trying to come up with a bunch of custom electronics to get around a problem that is easily fixed in an open source software.

ANT is an existing standard. You can buy off the shelf equipment that use ANT - you most commonly see it on heart rate monitors, exercise and bike equipment. It is the most common standard.

So I am suggesting something very simple: Don't try and build custom Mavlink things, just build a box that retransmits Mavlink into a standard like ANT so you can buy cheap and off the shelf equipment to work with it.

I do not want MP to connect to these devices, that would require a wire. I do not want to build my own (as some people have) heads up displays, I want to buy off the shelf. Adding mavlink to these would require a modem, therefore serial port, etc. Mavlink is not a widely adopted standard outside of UAVs.

Some equipment uses Bluetooth, and that problem has already been solved by these guys: http://diydrones.com/forum/topics/who-wants-a-iphone-app-used-as-a-...

I am suggesting to add to that scenario two new things:

  • Multiple radio support (fairly easy, just another serial port, extra bit of code)
  • ANT support (standard protocol used by lots of equipment)

Sorry it has not been clearer.

Scott

ANT seems like a wannabe bluetooth.  I wouldn't get locked into something that competes with established standards until you see if it catches on.  To me it looks like a straight rip-off of bluetooth.  They're extremely vague about what makes it different, what frequency it used, and what power levels.  Had to look at chipset datasheets for that, and it's just a bluetooth knock-off as far as I can tell.

just build a box that retransmits Mavlink

Again, I'm not seeing the point.  There is already serial -> bluetooth adapters that work just fine for about $7.  Everything has bluetooth, so no need to reinvent the wheel.  You can easily take multiple virtual com ports through bluetooth and switch to whatever one you want in the software.  No need for a special box.

ANT has been a standard a long time - can't find the exact start date. But if you have a wireless pedal sensor on a bike, it will likely be ANT. ANT is built into many Android tablets. 

My only reason for even remotely considering ANT is one thing - there is heads up displays being build now for Motorbikes and Bikes that use ANT - off the shelf ones. No building one - just buy it and wear it. 

I just don't see how it's really different from bluetooth.  I hate to support multiple competing standards for no reason.  It fractures the market and makes things more complicated and more expensive for no reason.

Look at smartphones.  They have to support cell, wifi, bluetooth, and gps already.  They have FOUR radios in them already for Christ's sakes!  So now we're expecting them to stuff ANOTHER one into them?  I just don't get it.

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